An electron-spin-resonance study of laser crystallized polycrystalline silicon

Brendel, K.; Nickel, N. H.; Lips, K.; Fuhs, W.

doi:10.1016/j.jnoncrysol.2004.02.082

Cited by 7 publications

(13 citation statements)

References 12 publications

(17 reference statements)

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“…Recently, it was reported that the resonance of the conductive electron with a g-value of about 1.988 occurs in laser-crystallized poly-Si for electron concentrations larger 5Â10 18 cm À3 [1]. In the following the analysis by Elliott will be applied to laser-crystallized poly-Si which was already reported for Ac-Si:H [13].…”

Section: Figurementioning

confidence: 88%

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Electronic transport in P-doped laser-crystallized polycrystalline silicon

et al. 2005

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Section: Figurementioning

confidence: 88%

“…The electronic properties of the grains were shown to be comparable to the single crystal state [1]. However, at the grain boundaries defects exists which where identified as silicon danglingbonds (db) [2].…”

Section: Introductionmentioning

confidence: 93%

Electronic transport in P-doped laser-crystallized polycrystalline silicon

et al. 2005

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“…In fact it was found that platelets do neither nucleate at nor cross grain boundaries [11]. On the other hand, silicon dangling-bonds form predominantly at grain boundaries [14].…”

Section: Methodsmentioning

confidence: 99%

“…To avoid ablation, amorphous silicon deposited at high temperatures or sputter deposited a-Si can be used for the crystallization process. The electrical properties of the resulting poly-Si samples are poor because of large concentrations of silicon dangling-bonds that are predominantly located at grain boundaries [2]. To obtain device grade poly-Si the samples have to be hydrogenated.…”

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Influence of laser crystallization on hydrogen bonding in poly‐Si

Nickel

Maydell

2008

Phys. Status Solidi (c)

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We investigate the influence of the hydrogen content in the amorphous starting material on hydrogen bonding and defect passivation in laser crystallized poly‐Si using electron‐spin‐resonance and hydrogen effusion measurements. After laser dehydrogenation and crystallization the specimens contain a residual H concentration of 8×1021 cm–3 to 1.5×1022 cm–3. During a vacuum anneal at least 1.5×1021 cm–3 H atoms are mobile in the lattice, however, only about 3.7×1018 cm–3 H atoms passivate Si dangling‐bonds. Our results show that the annealing treatment can cause the vast majority of H atoms to accumulate in H stabilized platelets. Since defect passivation preferentially occurs at grain boundaries and platelet nucleation and growth is confined to the interior of single crystal grains, H equilibration is governed by two spatially separated processes. Moreover, our data demonstrate that the hydrogen density‐of‐states distribution derived from H effusion data is dynamic and changes in response to experimental parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…ESR experiments performed on doped poly-Si showed that dangling bonds are predominantly located at the grain boundaries. 16 On the other hand, a detailed investigation on the formation of platelets in poly-Si revealed that these H stabilized two-dimensional structures form only in the interior of the grains. Moreover, the presence of lattice strain in the form of grain boundaries inhibits the formation of platelets.…”

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Hydrogen equilibration in polycrystalline silicon

Maydell

Nickel

2007

Applied Physics Letters

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Hydrogen equilibration in polycrystalline silicon was investigated as a function of annealing time and temperature using electron spin resonance and hydrogen effusion measurements. During a vacuum anneal at least 1.5ϫ 10 21 cm −3 H atoms are mobile in the lattice, however, only about 3.7ϫ 10 18 cm −3 H atoms passivate Si dangling bonds. The results show that the annealing treatment can cause the vast majority of H atoms to accumulate in H stabilized platelets. Since defect passivation preferentially occurs at grain boundaries and platelet nucleation and growth are confined to the interior of single-crystal grains, H equilibration is governed by two spatially separated processes. Moreover, the data demonstrate that the hydrogen density-of-states distribution is dynamic and changes in response to experimental parameters. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2716348͔The properties of hydrogen in silicon have attracted a great deal of interest. 1 This manifests itself in the neutralization of dopant atoms and the passivation of localized defects such as Si dangling bonds. The latter attribute is commonly utilized to improve the electrical and optical properties of polycrystalline silicon ͑poly-Si͒, which contains a high concentration of Si dangling bonds at grain boundaries. 2 On the other hand, prolonged exposure of poly-Si to monatomic H can cause deleterious effects such as the formation of electrical and structural defects. 3,4 In poly-Si identical crystallites are separated by grain boundaries. These two-dimensional extended defects contain deep and shallow localized states. Posthydrogenation treatments at moderate temperatures ͑e.g., 250-450°C͒ reduce the concentration of both classes of localized states and the kinetics of the grain-boundary passivation are consistent with diffusion limited passivation. 2 In addition to the passivation of localized states it has been shown that prolonged exposure of poly-Si causes deleterious effects such as the formation of acceptor-like states that leads to electrical-type conversion 3 and the formation of hydrogen stabilized platelets. 4 The latter effect is controlled by the Fermi energy. 5 In this letter, we present experimental evidence that merely the migration of hydrogen in poly-Si is sufficient to simultaneously cause beneficial and deleterious effects. A simple vacuum anneal results in a decrease of the Si dangling-bond concentration and the formation of large platelet-like structures. While the passivation occurs preferentially at grain boundaries the formation of platelets is confined to the interior of the grains. Hydrogen equilibration involves about 30% of all incorporated H atoms.Polycrystalline silicon thin films were prepared by the following procedure. First, hydrogenated amorphous silicon thin films were grown by rf glow discharge decomposition of silane ͑SiH 4 ͒ at substrate temperatures ranging from 160 to 335°C. Then the specimens were crystallized at room temperature and in high vacuum using the 308 nm line of an excimer laser a...

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An electron-spin-resonance study of laser crystallized polycrystalline silicon

Cited by 7 publications

References 12 publications

Electronic transport in P-doped laser-crystallized polycrystalline silicon

Electronic transport in P-doped laser-crystallized polycrystalline silicon

Influence of laser crystallization on hydrogen bonding in poly‐Si

Hydrogen equilibration in polycrystalline silicon

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